1. Field of the Invention
The invention relates to a waste compactor, in particular for compaction of bulk waste and garbage material such as plastics, paper, cardboard, wood and other compressible articles generally in a container such as a bag, box or a bin, for example, for disposal or recycling purposes.
The invention relates to a waste compactor of the type comprising an upwardly open waste container, a roller mounted on a support for movement within the container to travel over waste in the container for waste compaction, the roller being movable up and down in the container as waste builds up in the container. Waste compactors of this type are particularly suitable for compaction of waste on site as it is generated. They are generally convenient for loading and the compacted wasted can usually safely and easily be removed without any significant "spring-back" or movement of the waste as is sometimes the case with press type compactors.
2. Description of the Related Art
One such device is described in German Patent Specification No. DE 2,655,314 having a roller mounted on an arm within a container at a lower end of a screw which feeds waste to the roller for compaction. For pressing the roller against the garbage either the container may be fixed and the roller moved down onto the waste or the container may be raised up against the roller, the movement being affected by means of a piston or spring. The device is, however, somewhat complex and is unsuitable for relatively bulky waste materials which need to be broken up prior to feeding them into the compactor.
Another device of this type is described in patent specification No. EP 0,106,268. In this case, the roller is mounted on a vertical support arm which is supported co-axially within the container, the roller and support arm being freely movable axially within the container. The pressing of the roller against the waste is effected by only the weight of the roller acting on the surface of the waste within the container.
Similar pressing arrangements have been used in silage presses for a long time. Such an arrangement works reasonably effectively for a generally uniform material to which the construction of the roller can be matched. However, with a wide range of garbage or other waste materials as is often the case the operation may be somewhat unsatisfactory. With easily compressed materials the roller weight may be excessive causing the roller to dig into the garbage. With more robust waste materials, the weight of the roller may not be adequate to initially crush and then compact the garbage materials. Further, the central roller support arm may obstruct the feeding of waste materials to the roller. Also with this type of device, during start-up it is necessary to at least partially fill the container with waste as the roller needs to engage waste in order to circle around the vertical shaft and roll over the waste. If the roller is inserted first and then the waste goes in, the waste can gather on either side of the roller which remains stationary.
A further waste compactor of this type is shown in patent specification No. EP 0,315,674 in which the roller is mounted on an eccentric support arm which extends closely down along a sidewall of the container, a horizontal boom at a lower end of the arm carrying the roller at an inner end adjacent the container axis. While this construction provides less obstruction to the in-feed of garbage to the roller it is not entirely satisfactory as material can trap between the roller and the boom as the roller passes under the boom leading to increased stress and possibly jamming of the roller. Further, garbage can lodge on the horizontal boom or rest between the boom and a side of the container.
The use of cylindrical or substantially cylindrical rollers may in some cases cause problems due to slippage of an inner end of the roller on garbage at the centre of the container because of the differences in the relative speed of travel of inner and outer ends of the roller.
Also the relatively steep approach angle of a cylindrical roller to incoming garbage can cause problems with feeding the garbage between the roller and the compacted garbage to compress it, particularly with relatively bulky waste. Conventional rollers tend to push the garbage ahead of them rather than pulling it in under the roller.
Further, a cylindrical roller must be of a large diameter relative to the size of the un-compacted waste pieces (such as empty cardboard boxes for example), otherwise it may be unable to move over them and may instead become buried beneath them. Since the diameter of the roller must be relatively large (typically one half of the diameter of the compacting container), the roller is unable to travel close to the container walls without scraping off them at its mid-height. The apparatus is therefore obliged to leave a rim of relatively uncompacted material around a periphery of the waste container.
A problem can arise with the use of cylindrical garbage containers in that garbage items can be pushed around the sidewall of the container ahead of the roller.
The present invention is directed towards providing a garbage compactor which will overcome at least some of these problems.